WHERE to Find Data: Overview Strategies for Effective SQL Filtering

Photo by Omar Flores on Unsplash

Filtering in SQL involves selecting specific rows from a table or result set based on certain conditions. Filtering is a fundamental aspect of SQL queries and is typically done using the WHERE clause. Here's an overview of filtering in SQL:

I. WHERE Clause:

The WHERE clause is used to filter rows based on specified conditions. It appears after the FROM clause in a SQL query.

Syntax:

SELECT column1, column2, ...
FROM table_name
WHERE condition;

II. Comparison Operators:

Comparison operators are used in the WHERE clause to establish conditions for filtering.

• = (Equal):

WHERE column_name = value;

• != or <> (Not Equal):

WHERE column_name != value;

• < (Less Than):

WHERE column_name < value;

• > (Greater Than):

WHERE column_name > value;

• <= (Less Than or Equal To):

WHERE column_name <= value;

• >= (Greater Than or Equal To):

WHERE column_name >= value;